S.KEY595] AETIOLOGY 133
it occurred in 70 per cent (S. L. Si:npson). Ver_, e>ccabior;:;:K. large and
fatal haemorrhage occurs in such cases. Blood-stained sputum may be
associated with malignant tumours in the niediastinum. Non-n:a~'2n.ant
tumours in the chest, such as dermoid and lrrdatid c\sts. ma} cause
haemoptysis.
The symptom sometimes occurs in pulmonary abscess, not in earn
cases, but when a chronic abscess ca\ity has formed. At this stage there "'•'"*'
is often an associated secondary bronchiectasis. whicn ma\ ai times be
responsible for the bleeding.
Other rare causes are gangrene of the lung, rupture of an emp\enna Orhw
into a bronchus, and an abscess of the h\er v\hich hus perforated the ^'!,[^'ul't
diaphragm and the lung. Bullet or other penetrating wounds of the
chest and injuries of the lung with or without fracture of the ribs ma> be
responsible, and blood-stained sputum has been recorded in the rare
condition of spontaneous haemothorax.
Disease, especially stenosis, of the mitral valve uith chronic venous \fitial
engorgement of the lungs comes next in frequency to pulmonary
tuberculosis as responsible for haemoptysis. The breeding ma\ be due
to rupture of capillaries or small \essels into the air alveoli; and it is
noteworthy in this connexion that the pulmonarv \essels may show
arteriosclerotic changes in mitral disease. The extraxasated blood forms Pnlnioncuy
the solid purple masses called 'pulmonary apoplexies' by Laennec. aP°Pcx*
Local pleurisy over them often follows and may lead to a considerable
effusion which accounts for increasing dyspnoea. Emboli from a dilated
right auricle or from the abdominal or other veins may cause a haemo-
rrhagic infarct in the lung resembling a pulmonary apoplexy. The pres-
ence of congestive heart failure in mitral stenosis favours the occurrence
of such pulmonary infarction; in 52 cases of mitral stenosis examined
after death there were 23 with congestive heart failure, and of these
14, or 61 per cent, showed pulmonary infarction; whereas among
the 29 cases without congestive heart failure 2 only, or 7 per cent,
showed infarction (Levine and White). Primary thrombosis of branches
of the pulmonary artery may have a similar effect, though \vith a
slower onset. At necropsy it may be difficult to decide the relative
ages of a clot in a branch of the pulmonary artery and of a pulmonary
apoplexy or infarct in the area supplied by that vessel.
An aneurysm of the trans verse part of the aortic arch, or of the descend- Aortic
ing part near the attachment of the ductus arteriosus, may press on and amw*sm
cause ulceration of the walls of the trachea or of the left bronchus. A
large aortic aneurysm may excavate the lung and 'weep' into it. Ulcera-
tion into the trachea or bronchus may cause copious and suddenly
fatal bleeding; but sometimes there is leakage due to percolation of
blood between the laminated fibrin occupying an aneurysrnal sac, and
this may go on for a long time. An aneurysrn pressing on the left bronchus
is often quite small, but is prone by pressure on the left recurrent laryngeal
nerve to cause abductor paralysis, a suggestive sign.